You must read Pew Research Center surveys, i think you may find some research instrument to gauge  journalistic freedom and even media responsibility index.

In addition to PEW, which is an excellent resource, see:

Paris-based "Reporters without Borders" issues an annual "World Press Freedom Index". Visit http://en.rsf.org/. Also available in French, Spanish, Portuguese, Arabic, Farsi (?) and Mandarin Chinese.

U.S.-based "Freedom House" issues an annual "Freedom of the Press" and has an interactive called "Press Freedom by the Numbers".  Visit: https://freedomhouse.org/.

I suggest you http://www.amnestyusa.org/research/reports , they make several annual reports about press freedoom, internet censorship, etc. http://www.amnestyusa.org/our-work/issues/censorship-and-free-speech

I can suggest you a very good report of Journalistic Freedom you can base on, but it is in spanish. You can translate it and it could be very useful. There is an organization placed in Colombia called FLIP (Fundación para la Libertad de Prensa-Foundation for Freedom of the Press) and it gives plenty of figures and indicators about the freedom of the press in that country. Here is the link: http://flip.org.co/es/cifras-indicadores